Metalworking lubricant



Patented Mar. 25, 1952 2,590,451 METALWORKING LUBRICANT George L. Perry,Berkeley, Calif., assignor to Shell Development Company, San Francisco,Calif., a corporation of Delaware No Drawing. Application August 9,1947, Serial No. 767,860

1 Claim.

This invention relates to novel lubricants and methods of making them.More particularly this invention pertains to metal working or metalfabrication lubricants for use in rolling, drawing, forging of metalsand the like.

Problems encountered in lubricating metals under conditions referred toin the previous paragraph are particularly complex because of thevarious factors encountered such as high temperatures, excess pressure,emulsification, presence of foreign bodies or contaminants, work speedsand the like. To effectively lubricate under these adverse conditionsthe lubricant must act primarily as a coolant and lubricant.

In the field of rolling lubricants, palm oil was considered mostefficient and suitable. However palm oil has serious drawbacks in thatitis diflicult to remove from metal surface thereby requiring the use ofcleaners which greatly increases operating cost. Also it has a tendencyto stain surfaces which on annealing mars the surface and exerts adetrimental effect when such metals are to be subsequently tinned,alloyed and the like. In addition metal surfaces which become tooheavily coated with palm oil cause excessive slippage of the rollsthereby decreasing rolling efficiency. Palm oil is also very costly andscarce and a cheap and effective substitute for palm oil as a metalworking lubricant is greatly. desired.

To meet the requirements demanded of a good metal fabricating lubricantsuch as a roll lubricant, it must have high absorption properties (lowsurface tension) to adhere on wet metal surfaces even in the presence ofwater. Also enough reduction of friction coefiicient must be realized tokeep the mill from overheating.

Essential properties of such lubricants are: film strength, ability toreduce friction, ability to wet metals in presence of water, ability toproduce a good lustre on metal surface worked, ease of removal andnon-staining and de-emulsifying properties, i. e. separating from waterand contaminants.

Film strength When lubricated metal surfaces are forced to slide pasteach other under high pressures there is a tendency for surfaceasperities to penetrate the lubricant film and adhere; this in turnpermits the transfer of metal from one surface to another. Thisphenomenon known in metal working operation as pickup of the workedmetal by the die or roll may become very pronounced at elevatedtemperatures. Although high temperatures may be a result of highfriction and may lead to pickup, it is generally agreed that the abilityof a lubricant to prevent adhesion of metal surfaces is a propertydistinct from and not necessarily related to ability of the lubricant toreduce friction between sliding surfaces which do not adhere, For thisreason the ability of a lubricant to form surface films which preventactual -metal to metal contact and. adhesion is very essential.

Reduction of friction Roll lubricants must possess the ability to reducefriction between the rolls and the work sheet in order to reduce powerconsumption, prevent overheating and minimize the force which must beapplied to the rolls. The property of a lubricant to reduce friction isreferred as oiliness and depends upon the sheer strength of the filmformed on a metal surface and to the rheological behavior of thin filmsof oil when subjected to high pressures.

Wetabz'lity and adhesion Since roll lubricants are usually used inconjunction with water as a coolant, they must possess the property ofdisplacing water from metal surfaces and resist the washing action oflarge quantities of water applied to the rolls and work sheet. Oftenwashing water is applied in the form of a high pressure spray so thatthe ability of the lubricant to adhere to metal surfaces is of paramountimportance.

Lustre The appearance of the surface of rolled stock referred to inpractice as lustre" is markedly influenced by the character of the rolllubricant. To accomplish this, lubricants used for this purpose shouldbe non-staining and prevent microscopic tears on the worked metalsurface.

Ease of removal and non-staining A serious drawback of palm oil is thedifnculty of removing it from rolled metal sheets. Generallyelectrolytic cleaners are required to remove the palm oil for if it isleft on the metal surface and the metal is thereafter annealed the metalsurface becomes stained. Roll lubricants should therefore possess theproperty of being easily removed when desired and also not stain thesurface with which it is in contact, regardless of the temperature.

Corrosion resistant Efficient roll lubricants in additon to being ableto withstand high temperature and pressure must be non-corrosive duringthe rolling process and preferably act as a corrosion inhibitor afterthe rolling process, particularly in cases where the rolled metal isstored for long intervals before being further worked.

It is an object of this invention to provide an improved roll lubricantsubstantially superior to palm oil. It is another object of thisinvention to provide a lubricant for metal working which is stable andnon-corrosive. Still another object 9f this invention is to provide atacky metal working lubricant having the property of resisting beingdisplaced by water sprayed under pressure. Furthermore it is an objectof this invention to provide a metal working lubricant which isnon-staining and which can be easily removed from lubricated surfaces.

It has now been discovered that a metal work ing lubricant such as aroll lubricant can be prepared which possesses all of the above-desiredproperties and which in many respects is far superior to palm oil orroll lubricants containing as the main constituent palm oil and itsderivatives, by forming a stable blend of a waxy hydrocarbon essentiallynon-aromatic and a light liquid petroleum fraction, the viscosity ofwhich does not exceed around about that of gas oil. Stated somewhatdifferently it has now been discovered that excellent roll lubricantscan be obtained by blending a non-aromatic waxy hydrocarbon with aliquid hydrocarbon having a boiling range of between about 300 to 7&0"F. and preferably below 600 F. The two constituents are blended in suchproportions that the non-aromatic waxy hydrocarbon comprises a majorpart of the composition and preferably between 60 and 80% by weight,while the light liquid hydrocarbon comprises preferably about 20% andnot above 40% of the total blend, the more preferred being between 20%and 30%. The waxy hydrocarbon base when diluted with a minor amount of alight hydrocarbon such as gas oil should have a buttery consistency atlow temperatures but under conditions of use should possess the abilityof spreading through water and on to the sheet beinglubricated withoutcongealing or marring the surface. To this blend if desired substituentadditives having the property of imparting extreme pressure properties,stabilizing the blend against oxidation, corrosion, deterioration andthe like, may be added.

The main component of roll lubricants of this invention, namely, a waxyhydrocarbon or a hydrocarbon of wax consistency may be derived frompetroleum fractions such as petroleum distillates or residues, or thewaxy hydrocarbons may be produced synthetically by polymerization ofolefinic materials by the Fisher-Tropsch process or by dehydration oflong chain aliphatic alcohols having a minimum flash point of aroundabout 500 F. and which do not vaporize at elevated temperatures such asencountered in rolling of metals under high pressures and temperatures.

Waxy hydrocarbons may be recovered from suitable petroleum fractionssuch as Pennsylvania crudes, East Texas crudes, Mid-Continent crudes andthe like by de-asphaltizing the hydrocarbon and thereafter removing thewax from the asphalt free hydrocarbon fraction by any known suitablemeans. The asphalt may be separated from the oil either by distillationor solvent extraction although solvent extraction is preferred. In thisprocess a solvent is selected in which the oil is relatively soluble butin which the asphaltic materials are relatively insoluble. Among suchsolvents are the light liquid hydrocarbons such as ethane, propane,butane, as well as naphtha and gasoline. Oils treated with such solventsextract the oil and wax leaving behind the asphaltic materials asresidue. The wax-oil mixture may be removed from the asphalt-freesolution by chilling the solution, and then separating the precipitatedwax settling, filtering or centrifuging. Waxy materials thus producedare known in the art as slop waxes, petrolatumsto qk, 1

slack waxes, scale waxes, parafiin waxes, plate malcrystalline andneedle waxes, micro-crystalline waxes and the like. These waxes aredifferentiated from each other by the degree of de-oil ing to which theyare subjected and all of them may be used as one of the component partsof compositions of this invention.

De-waxing or separation of the above waxy constituents from the oil maybe accomplished by selective solvent treatment using as the diluentsliquefied normally gaseous hydrocarbons such as propane, butane, andother organic liquids such as alcohols, ethers, esters, ketones,aldehydes, acids and/or their mixtures. These may include methyl, ethyl,propyl, butyl, amyl alcohols; methyl or ethyl or methyl ethyl ether;acetones, diethyl, dimethyl, methyl ethyl, methyl isobutyl ketones andthe like. Chlorinated hydrocarbons such as carbon tetrachloride ortrichloroethylene and mixtures of chlorinated and non-chlorinatedhydrocarbons as mentioned above may be used.

The first step in obtaining waxy constituents from petrodeum crudes, forexample, such as Mid-Continent crude is to treat said crude withaboutsix volumes of liquid propane so as to remove the asphalt. Thepropane from the propane-oil, solution is vaporized so that the ratio ofpropane, to oil is reduced approximately 2 to l. Thesolution is thenchilled to about F. and lower causing separation of the wax from theoil. The waxv can be removed by filtration and the propane separatedfrom the de-asphalted and dewaxed oiland waxy material by distillation.A most. desirable wax fraction may also be obtained fromPennsylvaniawaxy steam cylinder stock by treating a waxy portion of said stock withmethyl ethyl ketone so as to obtain two fractions, one being dewaxed oiland the other fraction being what is known in the art as whole wax. Thiswhole wax is also treated with methyl ethyl ketone fromwhich again twoseparate fractions are obtained, one fraction being partially deoiledmicro-crystalline residue wax which contains about 5 to 6% oil and has amelting point ofabout 130 F. and the other fraction being the so-oalledslop wax or foots oil having a melting point of about 65 F. Themicro-crystalline waxes obtained from Pennsylvania waxy steam cylinderstock as disclosed in the previous sentences are mostly suited forrolling lubricants when blended with minor amounts, sufficient toinhibit congealing of the wax on the rolls and nips, of a lighthydrocarbon boiling below the lubricating range such as gas oil andlighter liquid petroleum fractions.

Waxy materials can also be recovered from distillate or residuum lubeoil fractions and these wax fractions can be split further into specialwax cuts having desired characteristics by use of selective solvents.This is based on a difference in solubility of different waxy fractionsin a given solvent. Thus when using a methyl ethyl ketone type solventthe aromatic constituents can be removed by successive cooling themixture down to between about 40 to C. so as to remove the aromaticswhich become substantially soluble in the solvent, as the temperature islowered while the straight chain waxes and isoparafiins becomesubstantially insoluble in the solvent. The straight chain waxes can beseparated from the isoparaffins by extraction and fractionalcrystallization. Depending upon the distillate cut used waxes of from 12to abov e 36 carbon atoms and higher can be obtained.

within the gas oil range.

Broad range Viscosity at 210 F 62-134 Flash, "F 490-560 Fire, F. 560-640Melting point, F -143 (25-70 preferred) M01. wt. 600 or higher Amount ofoil, percent Not more than 40% Amount of aromatic, percent 0-2% Waxcontent, percent 60-100% (65-80 pre ferred) Specifically preferred waxessuch as slop waxes have the following properties:

Ref. index, C 1.4796-1.4887

Percent solid wax 43-80% Percent liquids 20-57% Melting point 25-70 C.(25-40 0. preferred) Instead of obtaining natural waxes from petroleumin the manner indicated above, waxes can be produced synthetically bypolymerization of olefins under pressure or dehydrating long chain fattyalcohols such as octadecyl alcohol and the like. Thus waxes can beprepared by catalytically dehydrating octadecyl alcohol at between about375 to 450 F. to yield a mixture or mixtures of monomers and dimers ofC18 and C36 olefins. If desired'these'fractions may be separated fromeach other by atmospheric steam distillation at 550 to 590 F. andmoisture removed from the waxy fractions by any desired suitable means.

The diluent for the waxy base of this invention may be a liquidhydrocarbon having a boiling point below the lubricating oil range andpreferably a hydrocarbon having a boiling point The amount of diluentused should not amount to less than 20% and should not exceed 40% of theblend and preferably should be kept in the range of 24 to 36%. If lessthan 20% of a diluent is used congealing takes and above 40% the blendbecomes too fluid and is easily Washed away from the rollers, resultingin poor lubrication and appearance of the worked metal due to tearingaction exerted on the worked metal by the rollers.

Although light petroleum hydrocarbon fractions of the gas oil boilingrange are preferred as the diluent for the waxy hydrocarbon base otherdiluents such as mineral seal-oil, variouspetroleum naphtha cuts,mineral spirits, kerosene, kerosene S02 extract, petroleum ether,parafilnic hydrocarbons, e. g. normal hexane, dimethyl pentane, octane,iso-octane, undecane, dodecane, and the like may be used.

A preferred light hydrocarbon liquid has the following properties:

Flash, F 260 Viscosity at 100 F. U. S 46.5 Boiling range, F 490-700 Ablend of a waxy hydrocarbon and light petroleum hydrocarbon of thisinvention suitable as a rolling lubricant may have the followingproperties for a blend of 20% gas oil and 80% slop wax.

Flash, F 320 Fire, F. 350 Viscosity at 210 F. 57.6 V. I. Q 142 Meltingpoint, F. 92

These blends of waxy hydrocarbon and light petroleum hydrocarbon havinga boiling point below that of lubricating oil may be, if desired,fortified with improving agents such as minor amounts of:

A. High molecular weight fatty acids derived from animal, vegetable,marine oils, e. g.

1. Animal oil tallow lard bone neats-foot wool fat horse foot oils, etc.2. Vegetable oils castor cashew peanut cocoanut jojoba seed olive olivekernel palm oil palm kernel oils corn cottonseed kapok rapeseed ravisonsesame sunflower teaseed oil, etc. 3. Marine oils codfish codliverdogfish dolphin body dolphin fish herring J apfish menhaden porpoisebody and jaw oils salmon oil sardine and sardine liver oils seal oilshark and shark liver oils sperm whale body and head oils whale oil,etc.

B. Naturally occurring fatty acids of high molecular weights 1.Saturated capric' undecylic lauric myristic palmitic stearlc arachidiclignoceric cerotic montanic acids, etc. 2. Unsaturated oleic linolelcerucic linolenic brassidic elaidic V Substituted fatty acids ricinoleic,ricinelaidic hydroxystearic acids, etc.

was held between about 150 and 175 F. The total rolling pressure. wasmeasured with a constrained capsule-type pressure gauge placed betweenthe screw down and the bearing chock. The efliciency of each rolllubricant tested was determined from the ratio of total rolling pressurein pounds 100. extension in inches on the metal being worked. This ratiois a good comparative criterion of the coefiieient of friction developedby the lubricant on the worked surface.

Initial Total Exten- Ratio Pressure Roll Composition Pressure Pressuresion W Temper- Remarks (pounds) (pounds) (inches) 1 X 91151011 ature 1.Mineral lubricating 50,000 78.0 10 3 3.00 260 155 Unsulted for rolling.oil. Easily-washed away.

2. Gas Oil 50,000 1.57 155 Same as 1.

3. Commercial Niger- 50,000 33.8X10- 5.60 121 155 Diflicult to remove.ian Palm Oil. stains metals and has tsoliiie c ongeal' mg en eneies.

4. 80% Short Residue 50,000 82.0Xl0 11.1 77 0 155 Tends to only slight-Petrolatum and ly congeal, but does gas oil. not stain metal and easilyremove 5. 80% microcrystalline 50,000 82.0Xl0 3 8.2 80.3 155 No tendencyto conslop wax and 20% gas geal, does notstaiu oil. metal and is easilyremoved.

Test II D. Sulfur containing materials, e, g.

dibenzyl disulfide sulfurized sperm oil sulfurized cottonseed oilsulfurized fatty acids as listed under part B The above fortifyingagents maybe excluded from the rolling lubricant of this invention oradded to the roll lubricants in very minor amount generally notexceeding 10% of the total composition. Smaller amounts of fortifyingagents such as 1-2% are generally preferred.

To illustrate more clearly the present invention, the following examplesare presented. It is to be understood, however, that variousmodifications can be restored without departing from the spirit of theinvention as presented in the subjoined claims.

Test 1 Steel metal strips of standard size x 5") and gauge (.0102") wererolled on a rolling mill under an idling gage pressure of about 50,000pounds. The mill was run at a controlled speed, cooling water beingapplied also at a controlled rate and the lubricant tested applied at atemperature of about 200 to 240 F. The temperature of the rolls at theexit side of the roll nips Another method of determining the. efiiciencyof roll lubricant is by the lustre test: which is. a measure of thedegree of freedom from surface tearing during rolling of metals. Thedevice used consistsessentially of a light source from which light isdirected onto an area of a rolled sheet at 45, and the amount of lightreflected at 45 is measured with a G. E. photo-electric light meter.The. numbers recorded are, footcandles reflected light where thetheoretical perfect reflector would give a reading of approximatelyfoot-candles.

A black plate before being rolled has a reading of approximately 58foot-candles.

LUSTRE Ol? METAL PLATE AFTER BEING ROLLED WITH VARIOUS LUBRICANTS One ofthe most important properties of a good rolling oil in addition to itsnon-congealing properties and the ability of imparting lustre, a i. e.its ability to prevent the tearing of the metal during rolling, is itsability of being easily removed and not leave on the metal surfacelacquer-like stains on annealing.

To determine the lacquer staining properties of roll lubricatings thefollowing procedure was followed. A drop of oil was placed on a panel offully deoxidized black plate and inserted in a small tube furnace at 200F. with an atmosphere of dry, oxygen-free nitrogen. The temperature wasthen raised to 1225 F. and held for 9 20 minutes. The furnace was thencooled to 200 F. and the annealed panel removed and examined for stainscaused by the oil.

Composition Remarks 3. 80% mierocystallinc slop material formed onpanel.

wax+20% gas oil.

Rolling lubricants of this invention are well adapted as rust inhibitorsafter the rolled sheet has been worked.

The roll lubricant of this invention may be applied to the rolls of asheet metal rolling mill by any suitable means such as spraying,dripping or the like. It may be applied on the sheet metal prior to.during or after rolling. Preferably the lubricant is warmed to about atemperature of 150 to 175 F. before applying it to the rolls so as toaid in spreading the lubricant more evenly on the rolls and work piece.

In addition to being an excellent roll lubricant, compositions of thisinvention may be used as drawing lubricants, forging and die lubricantsand in various other processes where drawing and working of metalsrequires lubrication.

It is to be understood that while the features of the invention havebeen described and illustrated in connection with certain specificexamples, the invention, however, is not to be limited thereto orotherwise restricted'except by 10 the prior art and the scope of theappended claim.

I claim as my invention:

A metal fabricating lubricant consisting essentially of a blend of amierocrystalline slop wax and from 20% and 40% by weight of gas oil anda minor amount of from 1% to about 5% by weight of polyalkylene glycoldiester said diester compound being compatible with said blend.

GEORGE L. PERRY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,655,373 Keller Jan. 3. 19281,716,310 Gray a- June 4. 1929 1,920,161 Rosen July 25, 1933 2,126,128Montgomery Aug. 9, 1938 2,151,353 Montgomery Mar. 21, 1939 2,153,811Montgomery Apr. 11, 1939 2,203,507 Roehner June 4, 1940 2,210,140Colbeth Aug. 1, 1940 2,256,603 Wright Sept. 23, 19 1 2,258,930 HaefnerOct. 14, 1941 2,294,535 Burnwell Sept, 1, 1942 2,298,844 Schilling Oct.13, 1942 OTHER REFERENCES Chemicals by Glyco, Glyco Products Inc, 1944,pp. 15 and 25.

